The invention relates to a device comprising a core which is composed of parts of amorphous ferromagnetic metal and parts of non-amorphous ferromagnetic material and which comprises at least one bar-shaped leg which is surrounded by at least one coil wound from electrically conductive material, and also comprises a yoke which magnetically interconnects the end portions of the leg and whose cross-sectional area is larger than that of the leg.
A device of this kind is known from the abstract of JP-A-57-143-807 published in "Patent Abstracts of Japan", Vol. 6, No. 243 (E-145). The legs of the core of the known device are made of silicon iron and the yokes are made of amorphous metal. However, due to the core losses in the silicon iron, such cores are less suitable for use with comparatively high frequencies, for example 10 kHz and higher. Notably in the case of cores having comparatively large dimensions, the temperature of the core portion within the coil will become too high. The core losses of amorphous metal are substantially lower than those of silicon iron (approximately 70% lower). Therefore, it would be attractive to make the entire core of amorphous metal so that the temperature of the portions situated within the coil would not rise to such high values. However, such a core, which is known, for example from EP-A No. 0 127 119, has the drawback that the price of amorphous metal is high, so that the cost price of the core will also be higher.